Portable grinders of the straight type include a housing provided at its rear end with a handle and a power control means, such as a throttle valve in the case of a pneumatic tool. However, for getting a good control of the tool and to be able to apply a feeding force on the tool the operator also uses the forward end of the housing as an auxiliary handle. Normally, the grinder wheel guard is mounted on a coaxial neck portion of the housing and is secured thereto by means of a clamping device. This makes a rather non-ergonomic auxiliary handle, because the clamping device presents sharp edges and is not at all adapted to be a part of a handle. Thus, using the forward end of the housing as a handle has been far from comfortable for the operator.